You guys have made me curious about the oil. I have a mental note that in my F5 single speed axle I need a 140 weight oil. But of course I had to look it up to make sure. My Marmon Herrington lubrication chart has this note:

"GEAR OIL (GO) - Use a straight mineral base gear oil. For transmission, auxiliary transmission and axle differentials use SAE-140 for summer and SAE-90 for winter."

I am in central Florida so I will use 85w-140 year round.

Nelson

 

90W mineral oil is available here at Tractor Supply, but it only has a GL-1 rating so I opted for the 85-140W Mystic oil. GL-4 140W is available here also, but the Eaton manual said to use 140W when the temps are consistently over 100 degrees. Which wouldn't be a problem right now
Mark